The trick with this game, much like Blood Bowl is that you need to play to the strengths of your team. Basher teams need to bash and work on getting cards that help them to bash, reward them for bashing etc. I've played probably a dozen games now of various mixes and the only team that hasn't one yet is the Dwarfs. But before you worry about balance. Part of that is because Dwarfs through random luck haven't shown up as much and also because not every game has been with the same players so there has been a vast level of player experience in the different games.
I would have to say that the teams that have one the most are Humans, Elves and Orc's. But they area also the teams that have been showing up the most through random draw or selection depending on how we decide at the start of the game.
One final note is that with a few blowout victories when teaching new people the game all the scores have usually been very close. probably averaging a 4 point spread between the winner and the loser and most of the time that's come down to a last season/end of game upset.
So with that in mind the team/staff cards are pretty important and there is definitely a strategy that can be played built around collecting those types of cards. The more I play this game the more I'm seeing different strategize coming up.